Another high idle thread - how-to on butterfly plate springs?
Hey all. So, this issue has been plaguing me for years and I've finally decided it's time to tackle it.
Same old story. Car turns over perfectly every time, initially the idle is a smooth 750.
After some warm-up or driving, the idle will raise to 900-1000. Blipping the throttle doesn't help it. Shutting the engine off entirely and restarting it, however, does. If I get out and push the throttle arm closed in this state, it doesn't change anything.
This leads me to believe that it's not mechanical, to do with the quadrant arm, throttle spool, etc at this point, but rather perhaps vacuum related. All of my vacuum hoses are new and silicone (and have been recently done, without helping this issue).
I remember ages ago Elvis was quite hot on the notion of cleaning and maintaining the decel valves on the butterfly plates. I know that these might stick slightly and cause a higher idle.
My theory right now is that it makes sense that shutting the engine off entirely and restarting it would remove any air backpressure. This in turn is allowing them to close fully and resetting my timer on the high idle for a bit.
But now I can't find that thread he created about maintaining those springs. Getting the throttle body out is a fairly quick job, but I can't remember if he was advocating for new springs (and if so where to get them) or a good way to check/revitalize the existing ones.
Anyone have a link, a guide, or any other advice? My theory may also make no sense and I'm open to that. But this engine has been overhauled several times and all the new plugs, wires, injectors, fuel lines, water/vacuum hoses and gaskets in the world have not changed this one lingering issue.